This invention relates to an apparatus and to a method for transferring heat to an article by condensation thereon of a vapour, and more particularly but not exclusively to an apparatus and to a method for condensation soldering. Condensation soldering has been described in
(1) "Condensation Soldering" by R. C. Pfahl Jr., J. C. Mollendorf, and T. Y. Chu, published in Welding Journal, January 1975; PA1 (2) U.S. Pat. No. 3,866,307, and PA1 (3) Western Electric Engineer April 1975, article by T. Y. Chu et al, reference being directed to these publications which are incorporated by reference herein.
The heating of an article by condensation heat transfer requires the immersion of the article in the saturated vapour of a working liquid. If the temperature of the article is initially below the temperature of the saturated vapour, condensation takes place on the article with the consequent transfer to it of the latent heat of the vapour. Thus in condensation soldering hot vapour of a suitable liquid is used to transfer heat quickly, by use of the latent heat of condensation thereof, to a solder preform to melt the solder so that it flows under surface tension effects to make a soldered connection. The condensate of the vapour selected is immiscible with the molten solder so that condensation soldering provides a clean environment in which the soldering can take place.